Method of casting crank shafts



Sept. 10, 1935. D. J. CAMPBELL 2,014,224

' METHOD OF CASTING CRANK SHAFTS I Filed April 10,1935 5 Sheets-Sheet 1Eonidd Q fimbi AT ORNIIY6 Sept. I 10, 1935. D. J. CAMPBELL 2,014,224

METHOD OF CASTING CRANK SHAFTS Filed April 10, 1933 5 Sheets-Sheet 2INVENTOR Donakl d. Camp b ATTORNEYS Sept. 10, 1935.

D. J. CAMPBELL 2,014,224 METHOD OF CASTING CRANK SHAFTS Filed April 10,1933 5 Sheets-Sheet 3 H mvc'uron IDmki clfigmpbi arronuavs Sept. 10,1935. D. J. CAMPBELL ,2

METHOD OF CASTING CRANK SHAFTS Filed April 10, 1935 5 Sheets-Sheet 4INVENTOR 1) id c). 3 BY ona Campbu ATTORNEYS p 3 1 D. J. CAMPBELL2,014,224

METHOD OF CASTING CRANK SHAFTS Filed April 10, 1933 5 Sheets-Sheet 5INVENTOR Donald c3. Qnphel ATTORNEYS Patented Sept. 10, 1935 UNITEDSTATES PATENT OFFICE METHOD .OF CASTING CRANK SHAFTS of MichiganApplication April 10, 1933, Serial No. 665,391

2 Claims. (Cl. 22- 209) This invention relates to a method of castingirregular shapes, particularly crank shafts, cam, shafts and the like,and is primarily concerned with a practical method whereby cam shafts or5 crank shafts, having a sound, uniform, homogeneous structure, freefrom shrinks and draws, may be produced, and with which method the samemay be very economically and rapidly produced.

The method which I have invented includes as one very essential step thefeeding of molten metal from a reservoir therefor to the mold during theperiod of solidificationof the molten metal. And it is an object andpurpose of the invention to produce shafts of the character notedwherein the normal effects of shrinking and drawing, which would be veryconsiderable in elongated articles of this kind, are compensated by suchfeeding of the molten metal thereto. Accordingly, by use of my inventioncam shafts .or crank shafts for internal combustion engines of a uniformstructure throughout from one end to the other may be readily produced.

A further object and purpose of the invention is to pour the moltenmetal into a mold positioned substantially horizontal, whereby thepouring may be performed as rapidly as in any casting operation, andthen immediately turning the mold to a substantially vertical position,with the feeder reservoir of molten metal thereupon located at the upperportion of the mold, so that, with soldification of the shaft, feedingof molten metal thereto to obviate shrinkage which takes place with themold vertically positioned and with the elongated shafts in asubstantially vertical position. f

It is well known that in casting articles such as crank shafts or camshafts, the same being of elongated dimensions compared to theirtransverse dimensions, longitudinal shrinkage will take place after thepouring of the metal in the mold on cooling, resulting in a somewhatcoarse grain of the iron; and also inarticles of this class, which haveirregular shapes, shrinks and draws are caused at places where arelatively heavy section of metal joins a lighter section. Such shrinksand draws cause weaknesses in the shaft at such sections. With myinvention I obviate these faults and produce a cast cam or crank shaftwhich is sound and of a uniform, homogeneous structure throughout.

An understanding of the invention for the attainment of the objectsstated, as well as many others not at this time enumerated. may be hadfrom the following description, taken in connection with theaccompanying drawings, in which,

Fig. l is a plan view of a drag section of a mold for the casting of twocrank shafts.

Fig. 2 is a vertical longitudinal section through the complete mold,taken midway between its sides.

Fig. 3 is a plan viewof the drag section of a mold shown for casting oneshaft having exceptionally heavy crank flank portions.

Fig. 4 is a side elevation of the molding flask 10 used.

Fig. 5 is a plan view of a drag section of a mold for casting crankshafts having throws in different angular relations to'each other.

Fig. 6 is a similar plan view of a drag portion 15 of a mold for castingcam shafts.

Fig. 7 is a vertical cross section taken on the line :r-a: of Fig. 5.

Fig. 8 is a vertical cross section on the irregular line s-s of Fig. 1.

Fig. 9 is a traverse vertical section on the line i l-11 of Fig. 5.

Figs. 10 and 11 are similar vertical sections taken respectively on thelines zz and vv of Fi 5, and 1 Fig. 12 is a side elevation illustratinga lifting mechanism by means of which the mold is raised from itspouring position into a substantially vertical position immediatelyafter pouring.

Like reference characters refer to like parts in 30 the differentfigures of the drawing.

The mold used is an ordinary green sand mold, the sand being rammed ortamped into the flasks, the cope flask I being located over the drag 2and the same supplied with molding sand, the mold cavities being formedat the lower side of the sand 3 in the cope and at the upper side of thesand 4 in the drag. The flasks have projecting ears 5 with alinedopenings therethrou'gh to receive pins 6 for properly locating theflasks with respect to each 40 other, said pins passing through thealined openings.

The mold cavities I, as shown in Figs. 1, 3, 5 and 6, are provided inthe usual manner by using suitable patterns and at one end an enlargedcavity 8 is made which serves as a'reservoir for an excess of molteniron of the shaft. The gates 9, with branches l0 therefrom to differentparts in the length of the mold cavities, receive the molten iron, whichis drained through a skim gate 1 I to eliminate dirt and slag, themolten iron passing through a passage l2 leading to the upper side ofthe skim gate and the iron being poured into a riser opening at l3 inthe usual manner.-

It will be noted that the passage I: is turned 'subgate 9 for a distanceand then joins with the riser l3.

For regular constructions of crank shafts or.

cam shafts, what has been described applies in Figs. 1, 5 and 6. Butwith respect to crank shafts which have very heavy crank flank portions,additional mold cavities are provided by suitable parts on the patternsso as to provide reservoirs for molten iron to feed to said extra heavyflank portions, as shown in Fig. 3; and it will be noted that when themold is turned to a vertical position, by gravity molten iron will feednot only from the reservoir at 8 but also from the cavities at I 4 tothe shaft, that supplied at M going directly to the heavy flankportions.

With crank shafts which have throws at an angular relation to each otherthe mold is merely changed to provide therefonusing cores and as shownin Figs. 10 and 11 for parts of the crank shaft above and below thedivision line between the drag and cope.

The mold is rammed, the pattern drawn and the flasks with the moldsections therein brought together after the pattern has been removed inthe usual manner and thereafter placed horizontally on a suitable trucksuch as indicated in Fig. 12. A number of these trucks may be connectedtogether and pulled over a track to the pouring station, one afteranother, and the metal poured into the mold in the usual manner. Thecope section of the flask is provided with outwardly extending pins ortrunnions l5 located to one side of a plane midway between the ends ofthe flasks, with which pins an elevating apparatus is adapted todetachably connect as soon as the mold has been drawn away from thepouring station.

This elevating apparatus may be of any desired character but, as shownin Fig. 12, consists preferably of a pneumatic cylinder i9 having theusual tical or nearly vertical position.

Such change of position of the mold occurs immediately after pouring andbefore the molten metal has solidified, particularly before it hassolidified at the central portions of the iron which has been pouredinto the mold cavities. The reservoirs 8 will then be at the upper endsof the molten iron poured into the cavities and furnish abody of meltediron to feed to a shaft as the same begin to solidify, cool and shrinkat their outer sides, it of course being understood that the castingscool and solidify first at the walls of the mold cavities. counteractsthe shrinking which would otherwise take place if there were no feedersat 8 to supply molten metal against shrinkage; and likewise the, feedingfrom the molten metal in the cavities I 4 will feed the heav a P as ncrank shafts.

when the casting operation is completed and the casting has beensolidified the crank shafts 1a 'will be continuous in length and of theirregular shape shown, will be uniform in structure without shrinks ordraws. The gates 9 and I0, having 5 been filled with metal, will provideconnecting pieces in and Illa which may be readily separated from thefinished shafts and the feeder cavities at 9 and II will provideadditions to the shafts which will be cut away therefrom. 10

It will be noted that the angular position of the part I! of the pouringpassage to the length of the main gate 9 precludes the spilling out ofany molten metal other than what may be in the. riserv l3 and theadjacent passage 12 in the lifting 15 of the mold from horizontal tovertical position.-

It is to be understood that it is not necessary .for the mold to bepositioned horizontally. It

can be positioned at a slight angle to the horizontal quite as well, andthe invention should go not in any sense be limited to the locating ofthe mold in the first place in an absolutely horizontal position. Withthis invention cam shafts or crank shafts for internal combustionengines are readily and economically produced. The 25 pouring is notchecked in any way but may take place as rapidly as in any molding. Thefeeding of metal to the cooling casting from the upper end or at pointsin the length thereof by gravity eliminates undesirable shrinking anddraws in 30 the casting, and permits a control of the casting operationsuch that very close limits in sizes and dimensions may be observed. Thecasting produced even in such irregular shapes as engine crank shafts issound and is produced in much 35.

closer correspondence to the length of the'pattern used than heretofore,and with the use of my invention rapid quantity production may beattained.

I claim: I

1. The method of producing cast shafts which consists, in providing amold cavity in which to cast the shaft and further providing a cojoiningfeeder cavity of substantially the same at one end of the mold cavity,locating said mold in a substantially horizontal position and pouringmolten metal into said mold cavity to flll the same and the feedercavity, and then changing the position of the mold to substantiallyvertical position with the molten metal in the feeder cavity at theupper end of the molten metal filling said cavities to feed to the moldcavity while solidification is taking place.

2. The method of producing cast shafts which consists, in providing a.mold having a cavity corresponding to the shaft, and further providingthe mold with an enlarged feeding cavity at one end of the shaft cavity,locating the mold in a substantially horizontal position and pouringmolten metal therein to fill the same while in said position, and thenimmediately changing the

